Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/205—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase
  • C08J3/2053—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase the additives only being premixed with a liquid phase
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/30—Polarising elements
  • G02B5/3083—Birefringent or phase retarding elements
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
  • C08J2301/08—Cellulose derivatives
  • C08J2301/10—Esters of organic acids
  • C08J2301/12—Cellulose acetate

Definitions

• the present invention relates to a retardation film excellent in productivity and production stability, a method for producing the same, and a polarizing plate and a liquid crystal display device having the retardation film.
• LCDs liquid crystal display devices
• various optical films such as polarizing films and retardation films are used.
• a cellulose acylate film As a retardation film for a polarizing plate of a liquid crystal display (LCD), a cellulose acylate film is widely used.
• a cellulose ester solution hereinafter also referred to as a dope
• a dope is cast from a casting die onto an endless support (for example, a stainless steel belt or drum) that moves indefinitely, and the formed dope film (hereinafter also referred to as a web) is separated with a peeling roller (peeling point). After peeling, and then moving the web to the drying step, drying it while transporting it to form a cellulose ester film, and finally winding it into a roll with a winder to produce and store the cellulose ester film Was.
• a cellulose ester film containing silicon dioxide fine particles having a primary average particle diameter of 20 nm or less is disclosed in order to impart the slipperiness of the cellulose ester film (see, for example, Patent Document 1).
• Patent Document 1 a cellulose ester film containing silicon dioxide fine particles having a primary average particle diameter of 20 nm or less is disclosed in order to impart the slipperiness of the cellulose ester film.
• the addition amount of the matting agent is increased or applied from the viewpoint of imparting higher-order sliding properties. It was necessary to increase the particle size of the matting agent.
• a microscopic void called “craze” and an optical orientation disorder occur in the peripheral portion of the added matting agent particle.
• the film forming step has a step of forming a cellulose ester film containing a matting agent and a step of detecting the friction coefficient of the cellulose ester film immediately after winding, and in the film forming step, detection of the film friction coefficient from the detection step
• a method for producing a cellulose ester film that adjusts the amount of matting agent added to the dope based on the information has been disclosed (for example, see Patent Document 2).
• Patent Document 2 the slipperiness of the film relating to the winding quality of the cellulose ester film is detected in the production process of the cellulose ester film, and the result is reflected in the production conditions, for example, the content of the matting agent in the dope.
• the film when manufacturing a long roll, the film has a good winding shape and suppresses light scattering on the surface due to surface irregularities to obtain a high contrast retardation film.
• Technology development that can be done is eagerly desired.
• the present invention has been made in view of the above problems, and its solution is excellent in winding stability when producing a long laminated roll, and a high-contrast retardation film and a method for producing the same, It is to provide a polarizing plate and a liquid crystal display device provided with the same.
• the present inventor as a cellulose ester constituting the retardation film, contains a cellulose acylate having an acetyl group substitution degree in the range of 2.0 to 2.5,
• the surface unevenness (surface roughness Ra) is in the range of 0.5 to 2.0 nm, and the height of the uneven structure is extremely low.
• a long retardation film having a reduced surface haze and a high contrast can be stably produced without causing a winding slip or the like.
• the surface Martens hardness is within the range of 190 to 210 N / mm 2
• the arithmetic average roughness Ra of the A surface and the B surface is both within the range of 0.5 to 2.0 nm.
• a glass transition temperature lowering agent the glass transition temperature when the distribution of the glass transition temperature lowering agent in the film is unevenly distributed between the A plane and the B plane and measured by time-of-flight secondary ion mass spectrometry
• the value of the abundance ratio of the reducing agent is in the range of 1.1 to 1.5.
• the glass transition temperature lowering agent has a glass transition temperature lowering ability defined by the following formula (1) within a range of 3.5 to 5.0 (° C./part by mass), and the cellulose acylate with respect to 100 parts by mass. 3.
• Glass transition temperature lowering ability (XY) / 5 (° C./part by mass) [Wherein, X represents a glass transition temperature Tg 1 of a cellulose acylate film obtained by forming a cellulose acylate alone, and Y represents a glass transition temperature reducing agent for 100 parts by mass of the cellulose acylate. similarly formed into a film after adding 5.0 parts by weight represents the glass transition temperature Tg 2 of the obtained cellulose acylate film. ] 4).
• the retardation film according to any one of items 1 to 3, wherein an internal haze value is less than 0.03.
• a polarizing plate comprising the retardation film according to any one of items 1 to 4.
• a liquid crystal display device comprising the retardation film according to any one of items 1 to 4.
• a retardation film having excellent winding stability when producing a long laminated roll and having a high contrast a production method thereof, a polarizing plate and a liquid crystal display device using the same. it can.
• the cellulose ester constituting the retardation film is acetylated.
• a cellulose acylate having a group substitution degree in the range of 2.0 to 2.5 that is, diacetyl cellulose (hereinafter abbreviated as DAC)
• DAC diacetyl cellulose
• This DAC film has a high surface hardness (Martens hardness of 190 to 210 N / mm 2 ) compared to a triacetyl cellulose film (hereinafter abbreviated as TAC) and cellulose acetate propionate (hereinafter abbreviated as CAP).
• the uneven structure formed on the film surface is less likely to be crushed than TAC and CAP, and the matting agent oriented on the surface is Because it has the characteristic that it is hard to be buried inside the film, it can express the slipperiness by the matting agent more effectively, and as a result, it can express high contrast without excessively increasing the addition amount of the matting agent. At the same time, a long laminated roll can be manufactured stably.
• the retardation film of the present invention is composed of cellulose acylate having an acetyl group substitution degree in the range of 2.0 to 2.5.
• a surface and B surface Martens hardnesses are both in the range of 190 to 210 N / mm 2 , and the surface roughness (arithmetic average roughness) Ra of the A and B surfaces is 0.5 to 2.0 nm. It is in the range of.
• This feature is a technical feature common to the inventions according to claims 1 to 8.
• the retardation film of the present invention contains a glass transition temperature lowering agent from the viewpoint of further manifesting the effects of the present invention, and the distribution of the glass transition temperature lowering agent is the A plane and the B plane.
• Abundance ratio of the glass transition temperature lowering agent when measured by time-of-flight secondary ion mass spectrometry is preferably in the range of 1.1 to 1.5.
• the glass transition temperature lowering agent has a glass transition temperature lowering ability defined by the formula (1) in the range of 3.5 to 5.0 (° C./mass part) and is based on 100 parts by weight of cellulose acylate.
• the content is preferably in the range of 0.1 to 4.0% by mass.
• an internal haze value is less than 0.03.
• the transport speed of the retardation film in the stretching process is: It is characterized by being in the range of 100 to 225 mm / second. Furthermore, it is a preferable production condition that the amount of residual solvent of the retardation film at the time of peeling in the peeling step is in the range of 80 to 100% by mass.
• the retardation film of the present invention can be suitably provided for a polarizing plate.
• the polarizing plate of this invention can be comprised suitably for a liquid crystal display device.
• ⁇ is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
• ⁇ Phase difference film> The retardation film of the present invention, when acetyl group substitution degree contains cellulose acylate in the range of 2.0-2.5, the one surface of the film is A plane, B plane and the other surface, Both the A-plane and B-plane Martens hardnesses are in the range of 190 to 210 N / mm 2 , and the A-plane and B-plane surface roughness (arithmetic mean roughness) Ra are both 0.5 to 2.0 nm. It is in the range of.
• Martens hardness is a hardness measured in a state where a test load is applied (indentation), and is obtained from a value of a load-indentation depth curve when the load is increased. Martens hardness includes both plastic and elastic deformation components.
• Martens hardness is defined for quadrangular pyramid indenters and triangular pyramid indenters. Specifically, as shown by the following formula (2), it is defined as a value obtained by dividing the test load F by the surface area As that the indenter has entered from the contact zero point.
• Martens hardness F / As The Martens hardness is obtained from a load-indentation depth test, for example, in accordance with a method defined in ISO14577. An example of a specific measurement method is shown below.
• the temperature at the time of the test is 23 ° C.
• the indenter is pushed into the retardation film at a constant speed, and a load of 10 mN is applied.
• the Martens hardness is measured using a square pyramidal diamond indenter for the test piece.
• the Martens hardness is calculated by applying a load (10 mN) to the retardation film and dividing it by the surface area of the indenter that has entered beyond the contact zero point.
• One feature of the retardation film of the present invention is that the surface roughness (arithmetic average roughness) Ra of the A and B surfaces is in the range of 0.5 to 2.0 nm.
• the surface roughness Ra as used in the present invention can be measured using an optical interference type surface roughness meter (for example, RST / PLUS, manufactured by WYKO) according to JIS B0601: 2001, for example.
• an optical interference type surface roughness meter for example, RST / PLUS, manufactured by WYKO
• One feature of the retardation film of the present invention is to use cellulose acylate having an acetyl group substitution degree in the range of 2.0 to 2.5.
• cellulose acylate having a high degree of acetyl group substitution in this way, a film having a high surface hardness can be obtained, and at the same time, a high retardation development can be obtained and a retardation film having a high retardation can be obtained. Even so, it is possible to reduce the thickness.
• advantages such as the ability to keep the draw ratio low and avoid failures such as breakage can be obtained.
• Cellulose molecules are composed of many glucose units linked together, and the glucose unit has three hydroxy groups (hydroxyl groups).
• the number of acetyl groups derived from these three hydroxy groups (hydroxyl groups) is called the degree of acetyl group substitution.
• the cellulose acylate according to the present invention that is, diacetylcellulose (DAC), has an acetyl group bonded to an average of 2.0 to 2.5 hydroxy groups among the three hydroxy groups (hydroxyl groups) of the glucose unit. is doing.
• Examples of the cellulose acylate used in the present invention include carboxylic acid esters having about 2 to 22 carbon atoms, which may be aromatic carboxylic acid esters, but are particularly preferably lower fatty acid esters of cellulose.
• the lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms.
• the acyl group bonded to the hydroxy group (hydroxyl group) may be linear or branched, and may form a ring. Furthermore, another substituent may be substituted.
• the carbon number is preferably selected from acyl groups having 2 to 6 carbon atoms.
• the acyl group preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.
• cellulose acetate, cellulose propionate, cellulose butyrate and the like and those described in JP-A Nos. 10-45804, 8-231761, U.S. Pat. No. 2,319,052, etc. It is preferable to use mixed fatty acid esters such as cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate phthalate.
• the measurement of the degree of acetyl group substitution of cellulose acylate can be carried out according to ASTM D-817-91, and the preferred degree of acetyl group substitution is 2.18 to 2.45.
• the degree of acetyl group substitution of the cellulose acylate is 2.0 or more, an increase in the dope viscosity can be suppressed, an excellent film surface quality can be obtained, and a haze increase due to an increase in stretching tension can be suppressed. Moreover, if the acetyl group substitution degree is 2.5 or less, the required phase difference can be obtained.
• the number average molecular weight (Mn) of the cellulose acylate is preferably in the range of 30,000 to 300,000, since the resulting cellulose acylate film has high mechanical strength and is preferred. Furthermore, cellulose acylate having a number average molecular weight in the range of 50,000 to 200,000 is preferably used.
• the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw / Mn) of the cellulose acylate is preferably in the range of 1.4 to 3.0.
• the number average molecular weight (Mn) and the weight average molecular weight (Mw) of cellulose acylate are measured using gel permeation chromatography (GPC).
• Typical measurement conditions are as follows.
• the cellulose acylate according to the present invention can be obtained by synthesis by a known method. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.
• cellulose as a raw material for cellulose acylate, but examples include cotton linters, wood pulp (derived from coniferous trees, derived from hardwoods), kenaf and the like. Moreover, you may use the cellulose acylate obtained from them by mixing in arbitrary ratios, respectively.
• cellulose acylate examples include L20, L30, L40, and L50 manufactured by Daicel, and Ca398-3, Ca398-6, Ca398-10, Ca398-30, and Ca394-60S manufactured by Eastman Chemical.
• the retardation film of the present invention contains a glass transition temperature lowering agent, and the distribution of the glass transition temperature lowering agent is unevenly distributed on the A and B surfaces of the retardation film and measured with a time-of-flight secondary ion mass spectrometer. abundance ratio of the glass transition temperature lowering agent upon the (abundance abundance often face / glass transition temperature lowering agent in the glass transition temperature lowering agent is less surface), within the range of 1.1-1.5 Preferably there is.
• the retardation film of the present invention contains a cellulose acylate having a degree of acetyl group substitution within the range of 2.0 to 2.5 by containing a glass transition temperature reducing agent (hereinafter abbreviated as Tg reducing agent).
• Tg reducing agent glass transition temperature reducing agent
• the glass transition temperature Tg of the rate is lowered, and the workability and mechanical properties can be improved.
• Tg reducing agent by containing a Tg reducing agent, it is possible to improve the somewhat hard and brittle film properties of cellulose acylate having an acetyl group substitution degree in the range of 2.0 to 2.5.
• the Tg lowering agent used in the present invention is a value obtained by adding a glass transition temperature Tg 1 of cellulose acylate alone having a degree of acetyl group substitution not containing it to 2.0 to 2.5. It means a compound having the property of lowering the glass transition temperature, and any compound may be used as a Tg reducing agent as long as such a definition is satisfied.
• the value of the glass transition temperature Tg of the cellulose acylate film referred to in the present invention is a value measured by a differential scanning calorimetry (DSC).
• the glass transition temperature Tg can be measured according to JIS K7121, for example, using a differential scanning calorimeter DSC220 manufactured by Seiko Denshi Kogyo Co., Ltd.
• cellulose acylate alone or cellulose acylate containing a Tg lowering agent is set, and the temperature is raised from room temperature to 250 ° C. at 20 ° C./min under a nitrogen flow rate of 50 ml / min and held for 10 minutes. (1st scan), then the temperature was lowered to 30 ° C. at a rate of 20 ° C./min and held for 10 minutes (2nd scan), and further raised to 250 ° C. at 20 ° C./min (3rd scan).
• Each glass transition temperature Tg from the DSC curve of the 3rd scan obtained and obtained can be calculated
• a certain substance may or may not meet the definition of a Tg lowering agent.
• this compound Is defined as a Tg lowering agent.
• the Tg reducing agent according to the present invention has a glass transition temperature reducing ability (hereinafter abbreviated as Tg reducing ability) defined by the following formula (1): 3.5 to 5.0 ( ° C / part by mass), preferably 3.8 to 5.0 (° C / part by mass), more preferably 4.0 to 5.0 ° C / part by mass. Is within the range.
• the Tg lowering ability refers to the ability to lower the glass transition temperature Tg per unit mass of a certain substance, and is defined by the following formula (1).
• Glass transition temperature lowering ability (XY) / 5 (° C./part by mass)
• X represents a glass transition temperature Tg of a cellulose acylate film obtained by forming a cellulose acylate alone
• Y represents a Tg reducing agent with respect to 100 parts by mass of the cellulose acylate.
• the glass transition temperature Tg of the cellulose acylate film obtained by adding 5 parts by mass in the same manner is shown.
• Each glass transition temperature Tg can be measured using a differential scanning calorimeter DSC220 manufactured by Seiko Denshi Kogyo in accordance with JISK7121 as described above.
• Tg lowering ability of the Tg lowering agent is a value within the above range, an excellent Tg lowering effect can be exhibited even with a small addition amount. For this reason, it is possible to prevent the occurrence of problems such as bleed out that occur when a large amount of additive must be added.
• Tg reduction ability it is about 5.0 degrees C / mass part or less.
• the substance used as the Tg lowering agent is included in the preferred range of the above Tg lowering ability. Cases and cases where it is not included. In such a case, the substance is preferable as described above only when the substance is used in combination with cellulose acylate having an acyl group substitution degree of 2.0 to 2.5 when included in the preferable range of the above-described Tg reducing ability. It shall be interpreted as a Tg lowering agent that satisfies the range of Tg lowering ability.
• Tg lowering agent polyester compound>
• the specific form of the Tg reducing agent used in the present invention is not particularly limited as long as the definition of the Tg reducing agent described above (and preferably the preferable range of the Tg reducing ability described above) is satisfied.
• An example of the Tg lowering agent is a polyester compound represented by the following general formula (I).
• B represents a linear or branched alkylene group having 2 to 6 carbon atoms, or a linear or branched cycloalkylene group.
• A represents an aromatic ring having 6 to 14 carbon atoms, a linear or branched alkylene group having 2 to 6 carbon atoms, or a linear or branched cycloalkylene group having 2 to 6 carbon atoms.
• X represents a hydrogen atom or a monocarboxylic acid residue containing an aromatic ring having 6 to 14 carbon atoms.
• n represents a natural number of 1 or more.
• the polyester compound represented by formula (I) has an aromatic ring (6 to 14 carbon atoms), a linear or branched alkylene group, or a linear or branched cycloalkylene group (both having 2 to 6 carbon atoms).
• An alternating copolymer obtained by alternating copolymerization of a dicarboxylic acid and a linear or branched alkylene diol or cycloalkylene diol having 2 to 6 carbon atoms.
• aromatic dicarboxylic acid and the dicarboxylic acid having a linear or branched alkylene group or cycloalkylene group may be used alone or as a mixture, but from the viewpoint of compatibility with cellulose acylate. It is preferable that at least 10% or more of the aromatic dicarboxylic acid is contained. Alternatively, both ends may be sealed with a monocarboxylic acid having an aromatic ring (having 6 to 14 carbon atoms).
• dicarboxylic acid having an aromatic ring (6 to 14 carbon atoms) examples include, for example, phthalic acid, isophthalic acid, terephthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4 -Naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,8-naphthalenedicarboxylic acid, 2,2'-biphenyldicarboxylic acid, 4,4 ' -Biphenyldicarboxylic acid, etc.
• terephthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4′-biphenyldicarboxylic acid are preferable.
• dicarboxylic acid having a linear or branched alkylene group or cycloalkylene group (2 to 6 carbon atoms) examples include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and 1,2-cyclohexane.
• examples thereof include dicarboxylic acid and 1,4-cyclohexanedicarboxylic acid.
• succinic acid, adipic acid, and 1,4-cyclohexanedicarboxylic acid are preferable.
• linear or branched alkylene diol or cycloalkylene diol having 2 to 6 carbon atoms examples include ethanediol (ethylene glycol), 1,2-propanediol, 1,3-propanediol, 1,2- Butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6- Examples include hexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol. Among these, ethanediol (ethylene glycol), 1,2-propanediol, 1,3-propanediol, and 1,3-butanediol are preferable.
• A is preferably a benzene ring, naphthalene ring or biphenyl ring which may have a substituent from the viewpoint of excellent Tg lowering ability.
• the substituent that the benzene ring, naphthalene ring or biphenyl ring may have is an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.
• Examples of the monocarboxylic acid having an aromatic ring (having 6 to 14 carbon atoms) that seals both ends of the polyester compound include benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, p-tert-butylbenzoic acid, and dimethylbenzoic acid. Acid, paramethoxybenzoic acid, and the like. Of these, benzoic acid, p-toluic acid, and p-tert-butylbenzoic acid are preferable.
• Aromatic polyester compounds are prepared by the conventional methods of polyesterification reaction of dicarboxylic acid and alkylene diol or cycloalkylene diol, hot melt condensation method by transesterification, or interfacial condensation method of acid chlorides of these acids and glycols. It can be easily synthesized by any method. Furthermore, by adding the aromatic monocarboxylic acid described above, a polyester compound in which both ends are sealed can be synthesized.
• ⁇ Tg lowering agent benzodioxazine compound>
• a benzodioxazine compound represented by the following general formula (II) can be used as a Tg reducing agent.
• R 13 and R 23 each represent a substituent.
• k3 represents an integer of 1 to 5.
• m3 represents an integer of 0 to 4.
• Examples of the substituent represented by R 13 and R 23 include an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, an aryloxy group, an amino group, an alkylamino group, an arylamino group, and an alkylthio group.
• an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, an aryloxy group, and an alkylthio group are preferable, an alkyl group, an alkyloxy group, an aryl group, and an aryloxy group are more preferable, and an alkyl group An alkyloxy group is particularly preferable, and an alkyl group is most preferable.
• R 13 and R 23 are alkyl groups, alkyl groups having 1 to 8 carbon atoms are preferred. 1-4 alkyl groups are more preferred.
• the aromatic polyester compound represented by the general formula (I) and the benzodioxazine-based compound represented by the general formula (II) have been described in detail.
• any compound having a property of lowering the glass transition temperature in the range of 3.5 to 5.0 ° C./part by mass can be used as a Tg reducing agent.
• the amount of the Tg reducing agent added to the retardation film of the present invention is not particularly limited, but the content with respect to 100 parts by mass of cellulose acylate is in the range of 0.1 to 4.0% by mass. Preferably, it is in the range of 0.5 to 3.5% by mass. If the added amount of the Tg reducing agent is 1% by mass or more, the Tg reducing performance that is the original purpose of the Tg reducing agent can be sufficiently exhibited. On the other hand, if the addition amount of the Tg reducing agent is 5% by mass or less, the retardation development performance of the cellulose acylate film accompanying the increase in the addition amount of the Tg reducing agent can be prevented.
• the glass when measured by Time-Of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) between the A and B surfaces of the retardation film. It is preferable that the detected amount of the transition temperature lowering agent is biased.
• TOF-SIMS Time-Of-Flight Secondary Ion Mass Spectrometry
• the surface with a large amount of glass transition temperature lowering agent detected using time-of-flight secondary ion mass spectrometry is d A
• the surface with a small amount of glass transition temperature lowering agent detected is d B
• the r value represented by the following formula (3) is preferably in the range of 1.1 to 1.5.
• Time-of-flight secondary ion mass spectrometry refers to the ability to measure chemical information of atoms and molecules on a solid sample with a sensitivity of one molecular layer or less, and the distribution of specific atoms and molecules with a spatial resolution of 100 nm or less. This is an observable mass spectrometry method.
• Time-of-flight secondary ion mass spectrometry is a type of secondary ion mass spectrometry (SIMS), in which a solid sample is irradiated with a primary ion beam, and ions emitted from the outermost surface of the sample (two Analysis is performed by detecting (secondary ions). Since a time-of-flight mass spectrometer (TOF-MS) is used as the mass spectrometer, it is referred to as TOF-SIMS.
• TOF-MS time-of-flight mass spectrometer
• time-of-flight secondary ion mass spectrometry it is possible to measure a sample substantially non-destructively by irradiating the sample with an ion beam in a pulsed manner. It has been widely applied to the analysis of
• the r value represented by the above formula (3) may be in the range of 1.1 to 1.5, but is preferably in the range of 1.2 to 1.5, more preferably 1.3. Is in the range of -1.5, more preferably in the range of 1.4-1.5. If the r value is 1.5 or less, curling can be suppressed without producing an extreme difference in film physical properties (for example, expansion and contraction rate) on the front and back surfaces during the production of the polarizing plate.
• a Tg reducing agent is a concentration gradient along the thickness direction of the film.
• the form that exists with For example, as the simplest example, when the retardation film of the present invention is cut so as to be divided into two equal parts by a plane perpendicular to its thickness direction (a plane parallel to the plane direction of the film), a polarizer
• An embodiment in which the amount of the Tg-lowering agent present in the fragment containing the bonding surface is larger than the amount of the Tg-lowering agent present in the other fragment (fragment containing the other surface) is preferably exemplified.
• each piece An embodiment in which the amount of the Tg reducing agent present in is gradually decreased from the fragment containing the bonding surface with the polarizer toward the fragment containing the other surface is also preferably exemplified.
• the retardation film of the present invention is designed so that the r value defined in the present invention is in the range of 1.1 to 1.5, thereby further improving the adhesion with the polarizer constituting the polarizing plate. This can be further improved.
• cellulose acylate such as DAC having a low degree of acetyl group substitution is used not only as a retardation film but also as a retardation film that expands the viewing angle, it is laminated with a polarizer to form a polarizing plate. It is common to do. And when durability as a polarizing plate is considered, the adhesiveness between a cellulose acylate film and a polarizer is so preferable that it is high.
• the retardation film of the present invention is usually produced through a step of drying a cellulose acylate film obtained by casting a dope containing cellulose acylate and an additive on a support, peeling it, and then stretching it. .
• a production method is adopted in which the r value of the obtained retardation film is in the range of 1.1 to 1.5, one surface of the obtained retardation film is compared with the other surface. It was found that minute irregularities increased and a rough surface structure was exhibited.
• Tg lowering agent having a Tg lowering ability that lowers the glass transition temperature Tg of cellulose acylate is richly present on one side, so that the cellulose acylate moves flexibly during stretching. This is thought to be the result of the fact that And it is thought that the rough surface structure which has many such micro unevenness
• the bonding surface of the retardation film is subjected to alkali saponification treatment for the purpose of improving adhesion when the polarizer and the retardation film are bonded.
• the adhesion between the polarizer and the polarizer is improved by the mechanism as described above, so that it is expected that such alkali saponification treatment is unnecessary. The cost can be reduced by reducing man-hours.
• a part of the cellulose acylate present on the saponification treatment surface (bonding surface) of the retardation film may be hydrolyzed. If the alkali saponification treatment is not required, the possibility of hydrolysis of the cellulose acylate during the alkali saponification treatment is eliminated, and a very superior technique is provided.
• the phase difference film of the present invention it is characterized in that the surface roughness of the surface A and surface B (arithmetical means roughness) Ra is in the range of 0.5 ⁇ 2.0 nm both, film production
• the surface roughness Ra 1 of the A surface is It is preferably larger than the surface roughness Ra 2 of the B surface, and Ra 1 / Ra 2 is preferably 1.05 or more, more preferably 1.1 or more, and further preferably 1.2 or more. Most preferably, it is 1.3 or more.
• the retardation film of the present invention provides a certain solution to the above demand. That is, the retardation film of the present invention can alleviate a decrease in the degree of polarization of the polarizing plate due to the slight axial deviation when bonded to the polarizer. Although the mechanism is not completely clear, the following mechanism has been estimated according to the study of the present inventor.
• the Tg reducing agent contained in the retardation film of the present invention decreases the relative abundance of cellulose acylate that contributes to the development of retardation as the abundance in the film increases.
• the retardation values Ro and Rt of the retardation film are considered to be smaller than the macroscopic values for the entire retardation film. Conversely, if the vicinity of the other surface is observed microscopically, the values of Ro and Rt are considered to be larger than the macroscopic values for the entire retardation film.
• the retardation development performance as a whole film that is, the retardation values Ro and Rt are Is unchanged.
• the higher the retardation development performance as the retardation film, that is, the retardation values Ro and Rt the greater the decrease in the degree of polarization due to the axial misalignment with the polarizer.
• the Tg reducing agent is uniformly applied to the entire film.
• the degree of decrease in the degree of polarization of the polarizing plate is small. As a result, the decrease in the degree of polarization of the polarizing plate due to the axis deviation is alleviated.
• the retardation film of the present invention can contain other additives in addition to the above-described Tg lowering agent, as long as the objective effects of the present invention are not impaired.
• various additives applicable to the present invention will be described.
• the retardation film of the present invention can contain a hydrolysis inhibitor.
• a hydrolysis inhibitor By incorporating a hydrolysis inhibitor to a retardation film of the present invention, since the hydrolysis of the cellulose acylate is suppressed, thereby improving the water resistance of the retardation film.
• the hydrolysis inhibitor applied in the present invention means that the cellulose acylate having a degree of acetyl group substitution not containing a hydrolysis inhibitor and having a degree of substitution of 2.0 to 2.5 is hydrolyzable alone. Is any additive that can be prevented or inhibited by the above, and any substance may be used as a hydrolysis inhibitor as long as such a definition is satisfied.
• the mass reduction rate before and after saponification Measurement cards are used. Specifically, the retardation film is immersed in an aqueous potassium hydroxide solution having a concentration of 2.0 mol / L at 50 ° C. for 90 seconds, and the mass change rate of the retardation film before and after that is calculated. This mass change rate can grasp
• the mass change rate of the retardation film formed only with the cellulose acylate is d 1 %
• the mass reduction rate of the film in which 5 parts by mass of the additive is added to 100 parts by mass of the cellulose acylate is d 2 %.
• it can be determined that the additive is a hydrolysis inhibitor for cellulose acylate.
• cellulose acylate having a degree of acetyl group substitution within the range of 2.0 to 2.5 when a substance falls within the definition of the hydrolysis inhibitor and when it does not fall, If the substance is used in combination with a cellulose acylate having an acyl group substitution degree within the range of 2.0 to 2.5 in the case where it falls under the definition of the hydrolysis inhibitor, in the present invention, can do.
• the log P value here is also called an octanol-water partition coefficient or log Pow, and is defined as a common logarithm of the value of the ratio of the distribution concentration of a substance to each phase of a two-phase solvent system composed of n-octanol and water.
• the average log P value is determined by first considering the specific log P value of each compound constituting the mixture in consideration of the case where the hydrolysis inhibitor is used as a mixture of a plurality of compounds, and then the mixing ratio of each compound in the mixture. It is calculated by weighting by (mass ratio).
• the log P value is a value measured by a flask shaking method described in JIS Z-7260-107: 2000. Further, the logP value may be a value estimated by a computational chemical method or an empirical method instead of the actual measurement.
• the calculation method includes Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27, p21 (1987)), Viswanadhan's fragmentation method ( J. Chem. Inf. Comput. Sci., 29, p163 (1989)), Broto's fragmentation method (Eur. J. Med. Chem.-Chim. Theor., 19, p71 (1984)) ClogP method (reference documents Leo, A., Jow, PYC, Silipo, C., Hansch, C., J. Med. Chem., 18, 865, 1975) and the like are preferably used.
• Crippen's f agmentation method J.Chem.Inf.Comput.Sci., 27 vol., p21 (1987 years) are preferred. However, when the measured value by the flask shaking method mentioned above and the value estimated by the computational chemical method or the empirical method are significantly different, the measured value by the flask shaking method has priority.
• the average log P value of the hydrolysis inhibitor used in the present invention is preferably 7.5 or more, more preferably 8.0 or more, still more preferably 9.0 or more, and particularly preferably 9.5. That's it.
• the average log P value of the hydrolysis inhibitor is within such a range, an excellent hydrolysis prevention effect can be exhibited even with a small addition amount. For this reason, it is possible to prevent the occurrence of problems such as bleed-out that occurs when a large amount of additive must be added.
• the upper limit value of the log P value of the hydrolysis inhibitor is not particularly limited, but is preferably about 13.0 or less from the viewpoint of compatibility with cellulose acylate.
• hydrolysis inhibitor a sugar ester compound represented by the following general formula (III).
• G represents a monosaccharide or disaccharide residue.
• R 2 represents an aliphatic group or an aromatic group.
• m represents the total number of hydroxy groups (hydroxyl groups) directly bonded to the monosaccharide or disaccharide residues.
• n represents the total number of — (O—C ( ⁇ O) —R 2 ) groups directly bonded to monosaccharide or disaccharide residues, 3 ⁇ m + n ⁇ 8, and n ⁇ 0. .
• specific examples of the monosaccharide of the residue represented by G include, for example, allose, altrose, glucose, mannose, gulose, idose, galactose, talose, ribose, arabinose, xylose, lyxose Etc.
• disaccharide of the residue represented by G examples include trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, isotrehalose, and the like.
• the aliphatic group or aromatic group represented by R 2 may each independently have a substituent.
• n In the general formula (III), m and n need to satisfy 3 ⁇ m + n ⁇ 8, and preferably 4 ⁇ m + n ⁇ 8. Further, n ⁇ 0.
• the — (O—C ( ⁇ O) —R 2 ) groups may be the same as or different from each other.
• the aliphatic group in the definition of R 2 in the general formula (III) may be linear, branched or cyclic.
• the aliphatic group preferably has 1 to 25 carbon atoms, more preferably 1 to 20 carbon atoms, and still more preferably 2 to 15 carbon atoms.
• aliphatic group examples include, for example, methyl, ethyl, n-propyl, iso-propyl, cyclopropyl, n-butyl, iso-butyl, tert-butyl, amyl, iso-amyl, tert-amyl, n- Examples include hexyl, cyclohexyl, n-heptyl, n-octyl, bicyclooctyl, adamantyl, n-decyl, tert-octyl, dodecyl, hexadecyl, octadecyl, didecyl and the like.
• the aromatic group in the definition of R 2 in the general formula (III) may be an aromatic hydrocarbon group may be an aromatic heterocyclic group, more preferably an aromatic hydrocarbon group.
• the aromatic hydrocarbon group preferably has 6 to 24 carbon atoms, more preferably 6 to 12 carbon atoms.
• aromatic hydrocarbon group examples include benzene, naphthalene, anthracene, biphenyl, terphenyl and the like.
• aromatic hydrocarbon group benzene, naphthalene, and biphenyl are particularly preferable.
• the aromatic heterocyclic group those containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom are preferable.
• the heterocyclic ring include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline.
• aromatic heterocyclic group pyridine, triazine, and quinoline are particularly preferable.
• a four-headed colben equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube was mixed with 34.2 g (0.1 mol) of sucrose, 180.8 g (0.8 mol) of benzoic anhydride, 379. 7 g (4.8 mol) was charged, the temperature was raised while bubbling nitrogen gas from a nitrogen gas introduction tube with stirring, and an esterification reaction was carried out at 70 ° C. for 5 hours.
• the inside of the Kolben was depressurized to 4 ⁇ 10 2 Pa or less, and after excess pyridine was distilled off at 60 ° C., the inside of the Kolben was depressurized to 1.3 ⁇ 10 Pa or less and the temperature was raised to 120 ° C. Most of the acid and benzoic acid formed were distilled off. Then, 1 L of toluene and 300 g of a 0.5% by mass aqueous sodium carbonate solution were added, and the mixture was stirred at 50 ° C. for 30 minutes and then allowed to stand to separate a toluene layer.
• the hydrolysis inhibitor applicable to the retardation film of the present invention exhibits the effect of imparting water resistance to the film as described above. Therefore, it is preferable that this hydrolysis inhibitor is uniformly distributed throughout the film as much as possible, unlike the above-described Tg reducing agent.
• the detected value of the hydrolysis inhibitor on both sides (A side and B side) of the film, detected using time-of-flight secondary ion mass spectrometry will be expressed as d C , d
• the s value defined by the following formula (4) is preferably less than 1.1.
• this preferred embodiment of the deviation of the detected value of the hydrolysis inhibitor is basically a time-of-flight type on both sides of the retardation film. This means that the detected value of the hydrolysis inhibitor by secondary ion mass spectrometry is almost non-biased, specifically, only to the extent that the ratio is less than 1.1.
• the s value is theoretically a real number of 1 or more.
• the s value may be less than 1.1, but the s value is preferably 1.05 or less, more preferably 1.03 or less, still more preferably 1.02 or less, and particularly preferably 1. 01 or less, and most preferably 1.005 or less.
• plasticizer In the retardation film of this invention, you may contain a conventionally well-known plasticizer as needed from a viewpoint of obtaining the effect made into the objective of this invention.
• the compounds represented by the general formulas (I) to (III) are also used as plasticizers, but may contain other plasticizers.
• a polyhydric carboxylic ester plasticizer Preferably, a polyhydric carboxylic ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, a polyvalent It is selected from alcohol ester plasticizers, ester plasticizers, acrylic plasticizers and the like. Of these, when two or more plasticizers are used, at least one of them is preferably a polyhydric alcohol ester plasticizer.
• the polyhydric alcohol ester plasticizer is a plasticizer composed of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid ester, and preferably has an aromatic ring or a cycloalkyl ring in the molecule.
• a divalent to 20-valent aliphatic polyhydric alcohol ester is preferred.
• the polyhydric alcohol preferably used in the present invention is represented by the following general formula (IV).
• R 11 represents an n-valent organic group.
• n represents an integer of 2 or more.
• the OH group represents an alcoholic or phenolic hydroxy group (hydroxyl group).
• Preferred polyhydric alcohols include, for example, adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1, 2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, gallium
• monocarboxylic acid used for polyhydric alcohol ester there is no restriction
• Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.
• aliphatic monocarboxylic acid a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used.
• the number of carbon atoms is more preferably 1-20, and particularly preferably 1-10.
• acetic acid is contained, the compatibility with cellulose acylate is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.
• Preferred aliphatic monocarboxylic acids include, for example, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid, tridecyl Acids, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, etc., undecylenic acid And unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid.
• Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.
• aromatic monocarboxylic acids examples include those in which 1 to 3 alkoxy groups such as alkyl group, methoxy group or ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid or toluic acid, biphenylcarboxylic acid, Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as naphthalenecarboxylic acid and tetralincarboxylic acid, or derivatives thereof. Benzoic acid is particularly preferable.
• the molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. A higher molecular weight is preferable because it is less likely to volatilize, and a lower molecular weight is preferable in terms of moisture permeability and compatibility with cellulose acylate.
• the carboxylic acid used in the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.
• polyhydric alcohol ester examples include, for example, paragraph numbers (0084) to (0087) of JP2011-008296A and paragraph numbers (0076) to (0080) of JP2011-013699A. And Exemplified compounds 1 to 35 described in paragraph numbers (0096) to (0099) of JP2011-053645A.
• the glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used.
• alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl Ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl Glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl
• phthalate ester plasticizer examples include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.
• citrate ester plasticizer examples include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.
• fatty acid ester plasticizer examples include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate and the like.
• phosphate ester plasticizer examples include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like.
• the polycarboxylic acid ester compound is composed of an ester of a polyvalent carboxylic acid and an alcohol having a valence of 2 or more, preferably in the range of 2 to 20 valences.
• the aliphatic polyvalent carboxylic acid is preferably in the range of 2 to 20 valences, and in the case of aromatic polyvalent carboxylic acid and alicyclic polyvalent carboxylic acid, it is preferably in the range of 3 to 20 valences. preferable.
• the polyvalent carboxylic acid is represented by the following general formula (V).
• R 12 (COOH) m1 (OH) n1
• R 12 represents an (m1 + n1) -valent organic group
• m1 represents an integer of 2 or more
• n1 represents an integer of 0 or more
• a COOH group represents a carboxy group
• an OH group represents Represents an alcoholic or phenolic hydroxy group (hydroxyl group).
• Preferred examples of the polyvalent carboxylic acid include the following compounds, but the present invention is not limited to these.
• Trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal
• An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used.
• the alcohol constituting the polyvalent carboxylic acid ester compound that can be used in the present invention is not particularly limited, and known alcohols and phenols can be used.
• an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used.
• the number of carbon atoms is more preferably within the range of 1 to 20, and particularly preferably within the range of 1 to 10 carbon atoms.
• alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof
• aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used.
• the alcoholic or phenolic hydroxy group (hydroxyl group) of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid.
• the molecular weight of the polyvalent carboxylic acid ester compound is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750.
• the larger one is preferable in terms of improvement in retention, and the smaller one is preferable in terms of moisture permeability and compatibility with cellulose acylate.
• the alcohol used in the polyvalent carboxylic acid ester that can be used in the present invention may be one kind or a mixture of two or more kinds.
• the acid value of the polyvalent carboxylic acid ester compound that can be used in the present invention is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. By making an acid value into the said range, it is preferable from a viewpoint which can suppress the environmental fluctuation
• the acid value refers to the number of milligrams of potassium hydroxide necessary for neutralizing the acid (carboxy group present in the sample) contained in 1 g of the sample.
• As the acid value a value measured according to JIS K0070 is adopted.
• polyvalent carboxylic acid ester compound examples include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, and acetyl tribenzyl citrate. Rate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitic acid, tetrabutyl pyromellitic acid and the like.
• UV absorber In the retardation film of this invention, a ultraviolet absorber can also be contained as needed.
• the ultraviolet absorber is added for the purpose of improving the durability of the cellulose acylate film by absorbing ultraviolet rays of 400 nm or less.
• the transmittance at a wavelength of 370 nm in the retardation film is preferably 10% or less, more preferably 5% or less, and still more preferably 2% or less.
• Waves are not particularly limited as ultraviolet absorbers that can be applied to the retardation film of the present invention.
• oxybenzophenone compounds benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds
• examples thereof include compounds, nickel complex salts, and inorganic powders.
• the compound include 5-chloro-2- (3,5-di-sec-butyl-2-hydroxyphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl)- 6- (linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171, tinuvin 234, tinuvin 326 Tinuvin such as Tinuvin 327 and Tinuvin 328 are all commercially available from BASF Japan and can be preferably used.
• the ultraviolet absorbers preferably used in the present invention are benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, and triazine ultraviolet absorbers, and particularly preferably benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers.
• a discotic compound such as a compound having a 1,3,5 triazine ring is also preferably used as the ultraviolet absorber.
• a polymeric ultraviolet absorber can also be preferably used, and in particular, a polymer type ultraviolet absorber described in JP-A-6-148430 is preferably used.
• the method of adding the UV absorber may be added to the dope after the UV absorber is dissolved in an alcohol such as methanol, ethanol or butanol, an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane, or a mixed solvent thereof. Or you may add directly in dope composition.
• an alcohol such as methanol, ethanol or butanol
• an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane, or a mixed solvent thereof.
• a disperser such as a dissolver or a sand mill in a solution of the organic solvent and cellulose acylate, and then add to the dope.
• the amount of UV absorber used is not uniform depending on the type of UV absorber and the operating conditions, but when the dry film thickness of the retardation film is 30 to 200 ⁇ m, it is 0.5 to It is preferably in the range of 10% by mass, and more preferably in the range of 0.6-4% by mass.
• Antioxidant are also referred to as degradation inhibitors or stabilizers.
• the cellulose acylate film may be deteriorated.
• the antioxidant has a role of delaying or preventing the cellulose acylate from being decomposed by, for example, the residual solvent amount of halogen in the retardation film or phosphoric acid of the phosphoric acid plasticizer. It is preferable to make it contain in.
• a hindered phenol compound is preferably used.
• 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di- -T-butyl-4-hydroxyphenyl) propionate] triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], oct Decyl-3- (3,5-di-t-butyl-4-hydroxyphenyl
• 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred.
• hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.
• the amount of these compounds added is preferably in the range of 1 to 5000 ppm, more preferably in the range of 10 to 1000 ppm by mass ratio with respect to the retardation film.
• the retardation film of the present invention can contain an acid scavenger in the film.
• Any useful acid scavenger can be used without limitation as long as it is a compound that reacts with an acid to inactivate the acid.
• the epoxy described in US Pat. No. 4,137,201 is particularly useful.
• Compounds having a group are preferred.
• Epoxy compounds as such acid scavengers are known in the art and are derived by condensation of diglycidyl ethers of various polyglycols, particularly about 8 to 40 moles of ethylene oxide per mole of polyglycol. Examples include polyglycol and diglycidyl ether of glycerol. Also, in or together with the vinyl chloride polymer composition, metal epoxy compounds, epoxidized ether condensation products, diglycidyl ethers of bisphenol A (ie, 4,4′- Dihydroxydiphenyldimethylmethane), epoxidized unsaturated fatty acid ester and the like can also be mentioned.
• the epoxidized unsaturated fatty acid ester is particularly preferably an ester of a fatty acid having 2 to 22 carbon atoms and an alcohol having 2 to 4 carbon atoms, and examples thereof include butyl epoxy stearate.
• Others include epoxidized vegetable oils and other unsaturated natural oils that may be represented and exemplified by compositions such as various epoxidized long chain fatty acid triglycerides such as epoxidized soybean oil. These fats are also referred to as epoxidized natural glycerides or unsaturated fatty acids, and the fatty acids of these fats generally contain 12 to 22 carbon atoms.
• EPON 815C (made by Wako Pure Chemical Industries) can also be preferably used as a commercially available epoxy group-containing epoxide resin compound.
• acid scavengers that can be used include oxetane compounds and oxazoline compounds, organic earth salts of alkaline earth metals, acetylacetonate complexes, paragraphs (0068) to (0105) of JP-A-5-194788. The compounds described in are included.
• an acid scavenger may be called an acid scavenger, an acid capture agent, an acid catcher etc., in this invention, it can use without a difference by these names.
• a matting agent that can be applied in a range not exceeding 2.0 nm as the surface roughness Ra can be added to the retardation film of the present invention.
• Examples of the matting agent applicable to the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, and magnesium silicate. And inorganic fine particles such as calcium phosphate and crosslinked polymer fine particles.
• silicon dioxide is preferable from the viewpoint of reducing the haze of the cellulose acylate film.
• the primary average particle size of the matting agent is preferably 20 nm or less, more preferably in the range of 5 to 16 nm, and particularly preferably in the range of 5 to 12 nm.
• matting agents are preferably contained in the retardation film by forming secondary particles having an average particle size in the range of 0.1 to 5 ⁇ m, and more preferable average particle size is in the range of 0.1 to 2 ⁇ m. More preferably, it is in the range of 0.2 to 0.6 ⁇ m.
• the primary average particle size of the matting agent used in the present invention is measured by observing the matting agent particles with a transmission electron microscope (magnification of 500,000 to 2,000,000 times), observing 100 particles, and measuring the particle size. The average value is taken as the primary average particle size.
• a cellulose acylate film obtained by casting a dope on a support is dried, peeled, peeled and then stretched.
• the dope used for the production of the retardation film of the present invention contains cellulose acylate having an acyl group substitution degree in the range of 2.0 to 2.5 according to the present invention, and a Tg reducing agent as necessary.
• the Martens hardness on both surfaces of the obtained retardation film is 190 N / mm 2 or more, and the surface roughness (arithmetic average roughness) Ra of the A and B surfaces is 2.0 nm or less. It is characterized by being.
• the method for producing the retardation film of the present invention may be a method by a solution casting method or a method by a melt casting method, but is preferably a method by a solution casting method.
• cellulose acylate having an acyl group substitution degree in the range of 2.0 to 2.5 a Tg reducing agent and other various additives are dissolved in a solvent.
• a dope preparation step casting the dope onto an endless metal support that moves indefinitely, a drying step for drying the cast dope as a web, and peeling the web from the metal support It is manufactured through a peeling process, a stretching process for stretching the dried web in the width direction or the width direction, a second drying process for drying, and a winding process for winding the finished film into a laminated roll.
• the concentration of cellulose acylate in the dope is preferable from the viewpoint of reducing the drying load after casting on the metal support, but if the concentration of cellulose acylate is too high, the viscosity of the dope increases, The pressure load at the time of filtration may increase, leading to a decrease in filtration accuracy and filtration efficiency.
• the concentration of cellulose acylate that achieves both of these is preferably in the range of 10 to 35% by mass, and more preferably in the range of 15 to 25% by mass.
• a method of batch adding a specified amount to the dope preparation kettle is preferable.
• the solvent used for the preparation of the dope may be used alone or in combination of two or more, but it is preferable in terms of production efficiency to use a mixture of a good solvent and a poor solvent of cellulose acylate, A larger amount of good solvent is preferred from the viewpoint of the solubility of cellulose acylate.
• a preferable range of the mixing ratio of the good solvent and the poor solvent is that the good solvent is in the range of 70 to 98% by mass, and the poor solvent is in the range of 2 to 30% by mass.
• the good solvent or the poor solvent is defined as a good solvent that has the ability to dissolve the cellulose acylate used alone, and the poor solvent is a solvent that swells or does not dissolve alone. Therefore, the classification as a good solvent or a poor solvent changes depending on the degree of acetyl group substitution of cellulose acylate.
• the good solvent used in the present invention is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Particularly preferred is methylene chloride or methyl acetate.
• the poor solvent used in the present invention is not particularly limited, but for example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone and the like are preferably used. Further, it is preferable to include water in the dope within a range of 0.01 to 2% by mass.
• the solvent used for dissolving cellulose acylate can be reused. Specifically, the solvent removed from the film by drying in the film forming process can be recovered and reused.
• the recovered solvent may contain trace amounts of additives added to the cellulose acylate, such as plasticizers, UV absorbers, polymers, monomer components, etc. It can be used and can be purified and reused if necessary.
• additives added to the cellulose acylate such as plasticizers, UV absorbers, polymers, monomer components, etc. It can be used and can be purified and reused if necessary.
• a general method can be used as a method for dissolving cellulose acylate.
• heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure.
• Heating is preferably performed from the outside, and a jacket type is particularly preferable in terms of easy temperature control.
• the heating temperature of the dope after the addition of the solvent is preferably higher from the viewpoint of the solubility of cellulose acylate, but if the heating temperature is too high, the required pressure increases and the productivity decreases. .
• the preferable heating temperature is in the range of 45 to 120 ° C, more preferably in the range of 60 to 110 ° C, and still more preferably in the range of 70 to 105 ° C.
• the pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating.
• the pressure is adjusted so that the solvent does not boil at the set temperature.
• a method for dissolving cellulose acylate a method in which cellulose acylate is mixed with a poor solvent and moistened or swollen, and then a good solvent is further added and dissolved is preferably used.
• a cooling dissolution method is also preferably used, whereby cellulose acylate can be dissolved in a solvent such as methyl acetate.
• the cellulose acylate solution is filtered using a suitable filter medium such as filter paper.
• a suitable filter medium such as filter paper.
• the filter medium it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but if the absolute filtration accuracy is too small, there is a problem that the filter medium is likely to be clogged. Therefore, a filter medium having an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium in the range of 0.001 to 0.008 mm is more preferable, and a filter medium in the range of 0.003 to 0.006 mm is more preferable.
• the material of the filter medium there are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel can cause fibers to fall off. Less preferred.
• Bright spot foreign matter means that when two polarizing plates are placed in a crossed Nicol state, an optical film or the like is placed between them, light is applied from one polarizing plate side, and observation is performed from the other polarizing plate side. The point (foreign matter) that the light from the opposite side appears to leak.
• diameter of the number of foreign matter bright spots is 0.01mm or more 200 / cm 2 or less, more preferably 100 / cm 2 or less, further preferably 50 / m 2 or less, Particularly preferred is a range of 0 to 10 pieces / cm 2 . Further, it is preferable that the number of bright spot foreign matters having a diameter of 0.01 mm or less is small.
• the dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and under a pressure so that the solvent does not boil is the difference in filtration pressure before and after filtration.
• the rise of the is small and preferable.
• the preferred temperature range is within the range of 45 to 120 ° C, more preferably within the range of 45 to 70 ° C, and even more preferably within the range of 45 to 55 ° C.
• the filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.
• the r value determined from the detected values d A and d B of the Tg lowering agent on one side and the other side of the produced cellulose acylate film is as follows so that the r value is 1.1 or more.
• the first to third forms exemplified can be applied.
• the specific method of performing the above steps is not particularly limited so that the r value is 1.1 or more, and various methods as shown below can be selected or combined.
• first to third embodiments there are three typical embodiments (first to third embodiments), and the first embodiment is a method of controlling by the dope preparation conditions described below.
• This form is a method for controlling the process conditions after casting in a casting step described later
• the third form is a method using a co-casting method described later.
• first mode for setting the r value to 1.1 or more will be described.
• the second mode and the third mode will be described after the casting process described below, and the third mode will be described after the co-casting method described below.
• the above process can be performed by selecting various materials when preparing the dope. Specifically, as the essential components of the dope, there are three components, cellulose acylate, Tg lowering agent, and solvent. The material is selected so that the solubility parameter value of each of these three components satisfies a predetermined relationship. select. Thereby, in the obtained cellulose acylate film, the distribution of the Tg reducing agent can be biased in the thickness direction.
• Hansi solubility parameters of cellulose acylate, Tg reducing agent and solvent are HSP C , HSP G and HSP S in this order, the following formula (5) is satisfied.
• Each material may be selected.
• HSP Hansen Solubility Parameter
• HSP C HSP G
• Hansen Solubility Parameter (HSP) is a parameter developed by Charles Hansen to indicate the solubility of a substance.
• the Hansen Solubility Parameters HSP C , HSP G and HSP S have values as Hansen, Charles (2007).
• there may be a form in which the cellulose acylate, the Tg reducing agent and the solvent are each a mixture of two or more, but the values of HSP C , HSP G and HSP S in such a form are measured as a mixture. Adopted values.
• HSP G -HSP C is the absolute of the difference between the value HSP C solubility parameter values HSP G cellulose acylate solubility parameter of Tg-lowering agent Mean value.
• HSP G -HSP S means the absolute value of the difference between the value HSP S values HSP G and the solubility parameter of the solvent solubility parameter of Tg-lowering agent.
• the mechanism by which the distribution of the Tg reducing agent in the retardation film is biased in the thickness direction of the film is not completely clear, but the solubility parameter The closer the value is, the higher the solubility (affinity) means, and the following mechanism is presumed. That is, when dried on a metal support, the solvent gradually evaporates from the surface that is not in contact with the support (interface with air), so the concentration gradient of the solvent in the thickness direction of the cellulose acylate film Will occur. At that time, if the affinity of the Tg lowering agent for the solvent is higher than the affinity for the cellulose acylate, it is considered that the Tg lowering agent is biased toward the belt having a higher solvent concentration.
• is 1.1 times or more of
• is 1.2 times or more, and more preferably 1.5 times or more.
• the metal support used in the casting process is preferably a mirror-finished surface, and as the metal support, a stainless steel belt or a drum whose surface is plated with a casting is preferably used.
• the cast width can be in the range of 1-4m.
• the surface temperature of the metal support in the casting step is ⁇ 50 ° C. to less than the boiling point of the solvent, and a higher temperature is preferable because the web can be dried faster. However, if the temperature is too high, the web may foam or the flatness may deteriorate.
• the preferred support temperature is in the range of 0 to 55 ° C, and more preferably in the range of 25 to 50 ° C.
• the web is gelled by cooling and peeled off from the drum in a state containing a large amount of residual solvent.
• the method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of bringing hot water into contact with the back side of the metal support. It is preferable to use hot water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is shortened. When warm air is used, wind at a temperature higher than the target temperature may be used.
• process conditions drying step and peeling step after casting will be described as a second mode for setting the r value to 1.1 or more.
• the amount of residual solvent in the film at the time of peeling the cellulose acylate film from the support is reduced. That is, by drying under more severe conditions, the distribution of the Tg reducing agent can be biased in the thickness direction in the obtained cellulose acylate film.
• the peeling is performed under the condition that the residual solvent amount in the cellulose acylate film is within the range of 80 to 100% by mass at the time of peeling from the support.
• control by this 2nd form, and control by the 1st form (selection of the material at the time of dope preparation) mentioned above mentioned above.
• the residual solvent amount as defined above is defined by the following formula (6).
• M represents the mass of a sample of the web or cellulose acylate film collected at any time during or after production
• N represents the mass after heating the sample at 115 ° C. for 1 hour. Represents.
• Process conditions that are controlled so that the value of the residual solvent amount is not more than a predetermined value include drying conditions before peeling the film from the support.
• drying conditions There is no particular limitation on the specific form of the drying conditions before film peeling from the support, and it is appropriate to control the drying conditions so that the value of the residual solvent amount of the film at the time of peeling is within a predetermined range. If it is a trader, it can be carried out without any particular difficulty.
• the drying temperature is preferably in the range of 25 to 50 ° C., more preferably in the range of 35 to 45 ° C.
• the drying time is preferably in the range of 15 to 150 seconds, more preferably in the range of 25 to 120 seconds.
• the value of the residual solvent amount of the film at the time of peeling is not more than a predetermined value, conditions outside these ranges may be adopted.
• drying means employ
• a well-known knowledge can be referred suitably.
• Specific examples of the drying means include hot air, infrared rays, heating rollers, and microwaves, but it is preferable to carry out with hot air from the viewpoint of simplicity.
• the cellulose acylate film (web) peeled from the support is stretched.
• the peeling tension from a support body shall be 300 N / m or less.
• the film thickness and retardation value of the obtained cellulose acylate film can be controlled by adjusting the conditions during the stretching treatment.
• the retardation can be changed by lowering or increasing the tension in the longitudinal direction.
• the retardation can be changed by biaxially stretching or uniaxially stretching sequentially or simultaneously with respect to the longitudinal direction (also referred to as the film forming direction or casting direction) and the width direction of the cellulose acylate film. .
• the draw ratios in the biaxial directions perpendicular to each other are preferably finally in the range of 0.8 to 1.5 times in the longitudinal direction and 1.1 to 2.0 times in the width direction. More preferably, it is performed in the range of 0.8 to 1.1 times in the direction and 1.3 to 1.7 times in the width direction, and is performed in the range of 1.3 to 1.5 times in the width direction. It is particularly preferred.
• the stretching speed in the stretching step is preferably in the range of 100 to 225 mm / sec from the viewpoint of performing stable stretching and conveyance.
• the cellulose acylate film of the present invention is easy to stretch and may easily develop retardation, and has high resistance to process failures such as breaking.
• the temperature range during stretching is preferably within the range of 120 ° C. to 200 ° C., more preferably within the range of 130 ° C. to 170 ° C., and even more preferably over 140 ° C. to 160 ° C. or less.
• the range of the residual solvent amount in the cellulose acylate film during the stretching treatment is preferably in the range of 20 to 0%, more preferably in the range of 15 to 0%. More specifically, for example, it is preferable that the residual solvent amount is stretched by 11% at a temperature of 155 ° C., or the residual solvent amount is stretched by 2% at a temperature of 155 ° C. Alternatively, it is preferable to stretch at a temperature of 160 ° C. with a residual solvent amount of 11%, or at 160 ° C. with a residual solvent amount of less than 1%.
• the method for stretching the web is not particularly limited.
• a method of stretching in the vertical direction a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like.
• these methods may be used in combination.
• a tenter it may be a pin tenter or a clip tenter.
• the drying temperature after stretching is preferably 125 ° C. or higher, and more preferably 140 ° C. or higher. On the other hand, if it is 150 degrees C or less, it is preferable from a viewpoint which can suppress generation
• the manufacturing method by the solution casting method was mentioned as an example, it may be manufactured by the melt casting method from the viewpoint of manufacturing cost.
• a desired cellulose acylate film can be obtained by the control according to the second embodiment described above.
• melt casting methods by melt casting that are heated and melted without using the solvent used in the solution casting method (for example, methylene chloride, etc.) are melt extrusion molding, press molding, inflation, injection molding, blow molding. And can be classified as stretch molding.
• the melt extrusion method is excellent for obtaining a cellulose acylate film having excellent mechanical strength and surface accuracy.
• the specific method for obtaining the cellulose acylate web by the melt casting method and known knowledge can be referred to as appropriate.
• a retardation film in which the distribution of the Tg reducing agent is biased in the thickness direction can be produced by a co-casting method.
• the manufacturing method according to the third embodiment mainly includes a step of co-casting a plurality of dopes having different Tg lowering agent concentrations on a support, and drying a film obtained by casting. And it is comprised from the process extended
• a plurality of dopes including a cellulose acylate, a Tg reducing agent, and other additives are prepared.
• a dope A having a low concentration of the Tg reducing agent and a dope B having a high concentration of the Tg reducing agent are prepared.
• the metal support body layer side which is low concentration is just to co-cast on a support body so that it may become the metal support body layer side which is low concentration.
• each dope is laminated from one surface side to the other surface side in the order of increasing Tg reducing agent concentration. The form of performing is preferable.
• the cellulose acylate and Tg having an acetyl group substitution degree within the range of 2.0 to 2.5 are used.
• the retardation film having high Martens hardness which is a technical feature of the present invention, and having a high contrast has good slipperiness when laminated in a roll shape in the final winding process.
• the roll length per roll can be set long, High production efficiency can be obtained.
• the roll length per roll is preferably 4000 m or more, more preferably 4500 m or more, and particularly preferably 5000 m or more from the viewpoint of obtaining the high productivity of the present invention.
• the film thickness of the retardation film of the present invention is preferably a thin film, used in the range of 10 to 200 ⁇ m, preferably in the range of 10 to 100 ⁇ m, more preferably in the range of 10 to 60 ⁇ m. More preferably, it is in the range of 20 to 60 ⁇ m.
• the width of the retardation film of the present invention is preferably in the range of 1 to 4 m.
• the width is preferably in the range of 1.4 to 4 m, more preferably in the range of 1.6 to 3 m. If the width is 4 m or less, stable conveyance can be performed.
• the in-plane retardation value Ro and the retardation value Rt in the thickness direction can be obtained by the following expressions (7) and (8).
• n x represents a refractive index in a slow axis direction of the cellulose acylate film plane.
• n y represents a fast axis direction of the refractive index of the cellulose acylate film plane.
• nz represents the refractive index in the thickness direction of the cellulose acylate film. The refractive index is measured under the environment of 23 ° C. and 55% RH, and the measurement wavelength is 590 nm.
• d represents the thickness (nm) of the cellulose acylate film.
• the retardation values Ro and Rt were conditioned at 23 ° C. and 55% RH for 2 hours, and measured with an automatic birefringence meter (KOBRA21DH, Oji Scientific Co., Ltd.) from the vertical direction at 590 nm, It can be calculated from the extrapolated value of the retardation value measured in the same manner while tilting the cellulose acylate film surface.
• the retardation film of the present invention is different in retardation required depending on the required optical compensation effect, but from the viewpoint of taking advantage of high retardation development, the retardation values Ro and Rt are within the ranges specified below. It is preferable to satisfy.
• the retardation values Ro plane is preferably in the range of 30-70, more preferably in the range of 40-60, more preferably in the range of 45-55.
• the retardation value Rt in the thickness direction is preferably in the range of 90 to 230, more preferably in the range of 100 to 170, and still more preferably in the range of 110 to 160.
• the slow axis or the fast axis of the retardation film exists in the retardation film plane, and ⁇ 1 is preferably in the range of ⁇ 1 ° to + 1 °, where ⁇ 1 is an angle formed with the film forming direction. More preferably, it is within the range of -0.5 ° to + 0.5 °.
• This ⁇ 1 can be defined as an orientation angle, and ⁇ 1 can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments). If each ⁇ 1 satisfies the above range, high luminance can be obtained in the display image, and light leakage can be suppressed or prevented, and faithful color reproduction can be obtained in the color liquid crystal display device.
• the moisture permeability of the retardation film is preferably in the range of 300 to 1800 g / m 2 ⁇ 24 h at 40 ° C. and 90% RH, more preferably in the range of 400 to 1500 g / m 2 ⁇ 24 h, and 40 to 1300 g / m 2. -Especially within the range of 24h.
• the moisture permeability can be measured according to the method described in JIS Z0208.
• the range of the elongation at break of the retardation film is preferably within a range of 10 to 80%, and more preferably within a range of 20 to 50%.
• the range of visible light transmittance of the retardation film is preferably 90% or more, and more preferably 93% or more.
• the haze is preferably less than 1%, more preferably in the range of 0 to 0.1%.
• the internal haze is preferably less than 0.03, more preferably 0.001 or more and less than 0.03.
• the internal haze can be obtained according to the following method.
• the blank haze 1 (external haze value) of a measuring instrument other than the film is measured.
• the haze 2 (total haze value) including the sample is measured by the following procedure.
• the haze meter, glass, and glycerin used in the above measurement are as follows.
• Haze meter Measured using a haze meter (turbidity meter, model: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.).
• the light source was a halogen bulb of 5V / 9W
• the light receiving part was a silicon photocell (with a relative visibility filter)
• the measurement was performed according to JIS K-7136.
• the polarizer which is the main component of the polarizing plate of the present invention, is an element that passes only light having a plane of polarization in a certain direction, and a typical known polarizer is a polyvinyl alcohol polarizing film.
• the polyvinyl alcohol polarizing film includes those obtained by dyeing iodine on a polyvinyl alcohol film and those obtained by dyeing a dichroic dye.
• polarizer a polarizer obtained by forming a polyvinyl alcohol aqueous solution into a film and dyeing it by uniaxial stretching or dyeing and then uniaxially stretching, and then preferably performing a durability treatment with a boron compound may be used.
• the thickness of the polarizer is preferably in the range of 5 to 30 ⁇ m, particularly preferably in the range of 10 to 20 ⁇ m.
• the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%
• the degree of polymerization is 2000 to 4000
• the degree of saponification is 99.0 to 99.99 mol. %
• Ethylene-modified polyvinyl alcohol is also preferably used.
• an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature in the range of 66 to 73 ° C. is preferably used.
• a polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has few color spots, and is particularly preferably used for a large-sized liquid crystal display device.
• a polarizing plate can be produced by laminating a retardation film containing cellulose acylate having a degree of acetyl group substitution within the range of 2.0 to 2.5 of the present invention on one surface of a polarizer. it can.
• the surfaces of the cellulose acylate film at the time of bonding, it is preferable that the surface where the r value satisfies 1.1 or more and d A is detected is bonded to the polarizer. That is, of the two surfaces of the cellulose acylate film, the surface with the larger detection value of the Tg reducing agent by time-of-flight secondary ion mass spectrometry is used as the bonding surface with the polarizer.
• the cellulose acylate film according to the present invention may be used on the other surface of the polarizer constituting the polarizing plate, or another optical film is preferably bonded.
• other optical films include Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC8UA, KC6UA, KC4UA, KC8U, KC8U, KC8UCR, KC8UE, KC8UCR, -C, KC8UXW-RHA-NC, KC4UXW-RHA-NC (manufactured by Konica Minolta Opto).
• the polarizing plate of the present invention can be suitably used for a liquid crystal display device.
• the liquid crystal display device in which the polarizing plate of the present invention is used which has excellent optical compensation function, the contrast, since the excellent retardation film transparency is used, has excellent visibility.
• such a liquid crystal display device is excellent in durability because of high adhesion between the polarizer and the retardation film.
• Bonding between the surface of the polarizing plate on the cellulose acylate film side and at least one surface of the liquid crystal cell can be performed by a known method. Depending on the case, it may be bonded through an adhesive layer.
• the mode (driving method) of the liquid crystal display device is not particularly limited, and liquid crystal display devices of various drive modes such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB, and the like can be used.
• a VA (MVA, PVA) type liquid crystal display device is preferable.
• Example 1 Production of retardation film >> [Production of Retardation Film 101] (Preparation of fine particle additive solution) ⁇ Preparation of fine particle dispersion 1> Fine particles (Aerosil R812 manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin to prepare a fine particle dispersion 1.
• Fine particles (Aerosil R812 manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin to prepare a fine particle dispersion 1.
• Fine particle additive solution 1 The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. The masses of methylene chloride and the fine particle dispersion are as follows. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.
• Cellulose acylate having an acetyl group substitution degree of 2.45 and a weight average molecular weight Mw of 157500 was charged into the pressure dissolution tank containing the solvent with stirring. After heating and stirring, this was completely dissolved, and then Azumi filter paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. was used. The dope was prepared by filtration using 244.
• the dope was heated to a temperature of 33 ° C. and uniformly cast on a stainless steel belt support with a width of 1500 mm.
• the temperature of the stainless steel belt was controlled at 30 ° C.
• the peeled cellulose acylate film was stretched in the width direction using a tenter while applying heat at 160 ° C. with a stretching speed of 120 mm / second and a stretching ratio of 40%.
• the residual solvent at the start of stretching was 10% by mass.
• drying was completed while the drying zone was conveyed by a number of rollers.
• the drying temperature was 130 ° C. and the conveyance tension was 100 N / m.
• retardation films 102 to 125 In the production of the retardation film 101, the type of cellulose acylate, the type and amount of additive A (hydrolysis inhibitor), the type and amount of additive B (Tg lowering agent), the presence or absence of a matting agent, The retardation film 102 is similarly formed except that the stretching conditions (mm / second), the stretching ratio (%), and the residual solvent amount (% by mass) at the time of peeling are changed to the conditions shown in Table 1, respectively. ⁇ 125 were produced. Note that “PETB” which is the additive A2 shown in Table 1 is pentaerythritol tetrabenzoate.
• the log P value of the additive A (hydrolysis inhibitor) described in Table 1 is a value measured by the flask shaking method described in JIS Z-7260-107: 2000.
• the Tg lowering ability ⁇ Tg (° C./part by mass) of the additive B is a combination with the cellulose acylate to be used, according to JISK7121, using a differential scanning calorimeter DSC220 manufactured by Seiko Denshi Kogyo Co., Ltd. Tg was measured and determined according to the formula (1).
• Additive A1 Mixture obtained by mixing the sugar ester compounds (a1), (a2), (a3) and (a4) at a mass ratio of 1: 14: 35: 50 (a1: a2: a3: a4), average logP value: 9.1
• Additive A2 Pentaerythritol tetrabenzoate, average log P value: 9.9
• Additive A3 Mixture obtained by mixing the sugar ester compounds (a1), (a2), (a3) and (a4) at a mass ratio of 5: 19: 46: 30 (a1: a2: a3: a4), average log P value: 9.8
• Additive A4 Mixture obtained by mixing the sugar ester compounds (a1), (a2), (a3) and (a4) at a mass ratio of 48: 33: 17: 1 (a1: a2: a3: a4), average logP value: 12.4
• Additive A5 Mixture obtained by mixing the sugar ester compounds (a1),
• an ultra micro hardness tester manufactured by Fischer Instruments, product name “Fischer Scope 100C”
• Fischer Scope 100C Fischer Instruments, product name “Fischer Scope 100C”
• Measurement was performed by pushing the indenter into the retardation film at a constant speed and applying a load of 10 mN.
• the Martens hardness was calculated by applying a load (10 mN) to the retardation film and dividing it by the surface area of the indenter that entered beyond the contact zero point.
• the Martens hardness was measured according to the above method, and the surface hardness (Martens hardness) was determined for the A and B surfaces according to the following criteria.
• Both the A surface and the B surface have a Martens hardness of 195 N / mm 2 or more and 210 N / mm 2 or less.
• At least one of the A surface and the B surface has a Martens hardness of 190 N / mm 2 or more.
• ⁇ less than 195 N / mm 2 at least one surface of the a surface and B surface, a value Martens hardness exceeds less than 190 N / mm 2, or 210N / mm 2.
• haze 2 total haze value including the retardation film was measured by the following procedure.
• the haze meter, glass, and glycerin used in the above measurement are as follows.
• Haze meter Measured using a haze meter (turbidity meter) (model: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.).
• the light source was a 5V9W halogen bulb
• the light receiving part was a silicon photocell (with a relative visibility filter)
• the measurement was performed according to JIS K-7136.
• the cellulose acylate having a degree of acetyl group substitution within the range of 2.0 to 2.5 is used, and the Martens hardness and surface roughness on both sides of the film are defined in the present invention.
• the retardation film in the range has a low internal haze, excellent scattering resistance, and even when a long film of 7200 m is manufactured, compared to the comparative example, excellent sticking failure resistance and winding quality, and high quality.
• the phase difference film could be produced with high productivity.
• Example 2 ⁇ Production of polarizing plate> A 120 ⁇ m-thick polyvinyl alcohol film was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide, and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid, and 100 g of water, and then washed with water. A polarizer was obtained by drying.
• Example 2 the polarizer and the retardation films 101 to 125 prepared in Example 1 were bonded to each other according to the following steps 1 to 5, and Konica Minoltack KC4UY (cellulose ester film manufactured by Konica Minolopt Co., Ltd.) was bonded to the back side for polarization. Plates 101 to 125 were produced.
• Konica Minoltack KC4UY cellulose ester film manufactured by Konica Minolopt Co., Ltd.
• Step 1 Each retardation film and Konica Minoltak KC4UY were immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried to saponify the side to be bonded to the polarizer.
• Step 2 The prepared polarizer was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds.
• Step 3 Excess adhesive adhered to the polarizer in Step 2 was lightly wiped off and placed on each retardation film treated in Step 1.
• Step 4 Each retardation film laminated in Step 3, a polarizer, and Konica Minolta Tack KC4UY on the back side were bonded at a pressure of 20 to 30 N / cm 2 and a conveyance speed of about 2 m / min.
• Step 5 A sample obtained by bonding the polarizer prepared in Step 4 to each of the retardation films and Konica Minoltack KC4UY in a drier at 80 ° C. is dried for 2 minutes, and polarized light corresponding to the retardation films 101 to 125, respectively. Plates 101 to 125 were produced.
• the liquid crystal cell of this liquid crystal display device has a color filter on array structure in which a color filter and a thin film transistor are disposed on one of transparent substrates.
• the retardation film of the present invention is a retardation film having excellent winding stability, high contrast, excellent transparency, and high adhesion between the polarizer and the retardation film, so that it has durability. It can also be suitably used for liquid crystal display devices in various drive modes such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB.

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